“Confederacy of Crunches” is one of those Left 4 Dead 2 achievements that isn’t necessarily difficult, as much as it is tiring. To gain the “Confederacy of Crunches” achievement, you’ll need to play through and survive any L4D2 campaign using only melee weapons. This isn’t as difficult as it sounds, particularly if you play through the campaign on Easy mode, which is highly recommended. Single Player mode may make this achievement somewhat easier to gain, as the other players will not be bothered by the fact that you refuse to use firearms throughout the campaign.

Since “Dead Center” is somewhat shorter than other Left 4 Dead 2 campaigns, this may be the best campaign to play through to gain the “Confederacy of Crunches” achievement. Additionally, since you’re guaranteed to encounter a tank on your way through the campaign, you may be able to gain the “Confederacy of Crunches” achievement and the “Tank Burger” achievement (awarded for killing the tank using only melee weapons) at the same time.

One useful piece of advice for gaining the “Confederacy of Crunches” achievement is to avoid picking up any firearms altogether; that way you won’t accidentally switch over to one and ruin your progress (which can really turn you off of Left 4 Dead 2 for a while if it happens).